Returns the numeric value of the leftmost character of the string str. Returns 0 if str is the empty string. Returns NULL if str is NULL. ASCII() works for 8-bit characters.
SELECT ASCII('2');
50
SELECT ASCII(2);
50
SELECT ASCII('dx');
100
See also the ORD() function.
SELECT ASCII('2');
50
SELECT ASCII(2);
50
SELECT ASCII('dx');
100